In everyday situations, people make a multitude of memory errors. Among the errors people make is to erroneously believe they experienced events that never happened, often with great confidence. This basic fact about memory has broad implications for practices in applied situations. For example, if people erroneously believe they experienced events that never occurred, it casts doubt on the reliability of eyewitness memory and the authenticity of recovered memories of traumatic events (e.g., of childhood sexual abuse). Extensive evidence has accrued in recent years that people have great difficulty exterminating memory errors to information they never experienced, particularly if it is related to events they did experience. Further, these memory errors occur even when people are given explicit warnings to avoid errors and when they are instructed about how to distinguish between events they experienced and events that they did not. The research outlined in this proposal will evaluate the hypothesis that these memory errors occur because unstudied items become associated with perceptual information that was experienced during the encoding of related items. This hypothesis claims that the voice in which studied information is heard or the visual features used to present studied information are encoded and associated with memories of both the events that are experienced and events that are related, but that are not experienced. According to this hypothesis, when subjects are faced with related (but unstudied) items on a memory test, they will often retrieve evidence that the item was perceptually experienced, leading them to erroneously believe the item was studied. Thus, if the representations of unstudied items are associated with perceptual features present during encoding, subjects will have little basis to distinguish between studied and unstudied information, and will make a large number of memory errors. In the studies proposed here, multiple memory tests will be used to explore the nature of the memory representations underlying memory errors. In particular, memory tests that have been shown to be sensitive to the perceptual information encoded in memory will be used. Thus, these tests can be used to determine whether or not the representations of unstudied information become associated with perceptual information when related information is encoded. The results of these studies will provide a better understanding of the characteristics of the representations underlying memory errors, which in turn will inform techniques for eyewitness interviewing and clinical views of recovered memory reports. The results of these studies will have implications for assessing the authenticity of eyewitness memory accounts and recovered memories of past traumas, which often contain vivid perceptual detail. To the extent that events that were not experienced are shown to be associated with perceptual details of related study experiences, it will suggest that retrieval of vivid perceptual details can occur in the absence of actually experiencing an event. Such a result will suggest that even when eyewitness memory accounts and recovered memories of past traumatic events are accompanied by vivid recollections of perceptual detail, those memories may not be accurate. [unreadable] [unreadable] [unreadable]